Flavorants are commonly added to cigarettes and other smoking articles, during the manufacturing process to achieve desired taste and smell sensations during smoking. Many tobacco flavoring materials, including the commonly employed menthol flavorant, however, are volatile and tend to vaporize and gradually escape from the cigarette between the time the cigarette is made and the time it is smoked.
One method employed to compensate for this loss of flavorant over storage time involved applying a greater amount of the flavoring material to the cigarette during its manufacture. However, when the cigarette is stored for an extended period or subjected to varying conditions of temperature and humidity prior to smoking, a significant loss of flavor occurs resulting in failure to achieve the desired taste and smell sensations upon smoking.
Other flavor release methods which have been employed in smoking materials fall into four categories, including the use of compounds or complexes which decompose to release the flavorant, the use of capsules rupturable upon the manual application of pressure thereof which contain the flavorant, flavorants, releasable upon thermal activation and encapsulated flavors released by moisture application.
In one exemplary cigarette construction described in U.S. Pat. No. 3,006,347, a flavor is encapsulated in a film forming vehicle having as its basic chemical constituent a polysaccharide, a polypeptide, or mixtures thereof. The encapsulated flavor is applied to the cigarette paper. The flavor is released by heating the vehicle to a temperature sufficiently high to degrade the film-forming vehicle structure. Thus, the useful application of the flavor and vehicle is limited to only those regions of the cigarette that will experience sufficiently high temperatures during smoking, such as the tobacco filler itself or the cigarette paper surrounding the filler. Moreover, the temperatures required to destroy the vehicle structure and release the flavor are sufficiently high to permit flavor release only in the vicinity of the coal. Thus, the flavor must be applied along the whole length of the tobacco rod wrapper to ensure a consistent level of release and delivery of flavor during smoking. Such a vehicle is difficult to apply to the cigarette paper during cigarette manufacture.
There remains, therefore, a need in the art for methods and materials enabling the retention of volatile flavoring materials in smoking articles under a variety of storage conditions and durations.